J.R. Young. R.W Jordan. L. Cros.: Notes on narmoplankton systematics... , p. 89- 99.

Journal of Nannoplankton Research, 20, 2, 1998.

NOTES ON NANNOPLANKTON SYSTEMATICS AND
LIFE-CYCLESCERATOLITHUS CRISTATUS, NEOSPHAERACOCCOLITHOMORPHA AND UMBILICOSPHAERA SIBOGAE
Jeremy R. Young*, Richard H;: Jordanf & Llulsa Cros"*Palaeontology Dept., 111e Natural History Museum , Cromwell Road, London SW? 5BD, UK; fDept. of Earth &Environmental Sciences, Yamagata University, Yamagata 990 8560, Japan ; "Institut de Ciencias del A1ar (CSJC),
Passeig Joan de Borbo sin., 08039 Barcelona, Spain

Abstract: Ceratolithus crista/us is known to produce both ceratoliths and hoop-shaped heterococcoliths.
More recently, evidence has b een given that a planolith-bearing heterococcolithophore, conventionall yreferred to the separate species Neosphaera cocco /ith o morpha. is an a lternate life-cycle phase of C.
crista/us. The evidence for thi s is outlined, and supported by new exa mples of as so ciations of thedifferent lith types. The type description of N. cocco /ithomorpha is reassessed and it is shown that thename is a junior synonym of Umbilicosphaera sibogae rather than a senior synonym of C. cri status. The
diversity of lith types produced by C. cri status is reviewed and th e structure and geological range of theplanolith heterococco liths is di scussed.

Introduction
One of the most interesting developments of recent
research on nannoplankton has been the recognition of
an increasing number of associations of supposedly
different species, related apparently to complex life-cycles(Kleijne, I991; Thomsenetal., 199l;Billard, 1994;Alcober& Jordan, 1997; Cros et al. , in press). These are providing
invaluable new perspectives on nannoplankton biology(Cros et al., in press), but also create new taxonomic
problems. We discuss here the rather complex implicationsof an association involving Cerato/ithus cristatus and
Neosphaera coccolithomorpha.
Alcober & Jordan (1997) described unusual coccospheres consisting of N. cocco/ithomorpha coccoliths
together with the hoop-shaped coccoliths of C. cri status.
They suggested that this was not a chance association
but rather evidence of a complex life-cycle with the one
algal species being capable of producing three different
types oflith: (I) The robust horseshoe-shaped ceratoliths
well known to palaeontologists; (2) the delicate hoopshaped heterococcoliths described by Norris (1965) and,since, frequently recorded both in association withcerato1iths and as separate coccospheres (e.g. Norris, 1971;
Alcober & Jordan, I997); (3) the larger more robust
heterococcoliths of N. coccolithomorpha. These are often
described as circular placoliths with the distal shield
missing, but following the terminology of Young et al.
( I997) they may more usefully be termed planoliths.
Alcober & Jordan (1997) believed that the N.
cocco/ithomorpha - C. cristatus association was
biologically meaningful but finally concluded that, owing
to the absence of definite evidence (they only had one
unambiguous specimen), nomenclatural changes would
be premature. They noted. however, that N. coccolithomorpha Lecai-Schlauder, 1950 had priority over C.
crista/us Kamptner, I950 since the actual publication dates
were, respectively, 30th March, I950 (recorded printing
date, from inside cover of the journal part) and later than
30th April, I9 50 (the journal part includes weather records

Cros et al. (in press) discovered a further combination coccosphere clearly showing the N. coccolithomorpha - C. cristatus association. From this, they concluded that this association can now be consideredestablished. In addition, we have since found further
combination coccospheres showing the association (Plate
2, Figures 2, 3) in plankton samples taken off SW Puerto
Rico in February and April , 1995. Clearly nomenclatural
clarification is now necessary.
Identity ofthe species described by Lecai-Schlauder(1950) as N. coccolithomorphaRe-examination ofLecal-Schlauder (1950) led us to realisethat the species described by her as N. coccolithomorpha
might not be the taxon usually termed N. coccolithomorpha, but in fact Umbilicosphaera sibogae var.
sibogae Weber-van Bosse, 190 I . This interpretation was
also given by Gaarder ( 1970); when proposing the new
combination Umbi/icosphaera sibogae, she wrote,Neosphaera cocco/ithomorpha Lecal-Schlauder (I949,
p.l65, figs 4-6) should also be included in this species".
The type illustrations ofLecal-Schlauder (19 50) are
reproduced here as Plate I , Figures 1-4. The conunon species
concept of N. coccolithomorpha has been based on thedrawing (Plate I , Figure 3). However, the photograph ofthe coccosphere (Plate I , Figure 4) should be regarded as
the holotype and this specimen resembles V. sibogae var.
si bogae. A comparative micrograph of an V. si bogae var.
sibogae coccosphere is given in Plate 1, Figure 5 (courtesyof Prof. Inouye) and shows the striking similarity. The
following additional points support the interpretation of
N. coccolithomorpha as a junior synonym of U. sibogae:
I. In the LM, it is not easy to make accurate observations on coccospheres. In particular, with placoliths andsimilar coccoliths, the tube is usually prominent but theshields are hard to distinguish , even with modern
microscopes. The problems caused by this are obvious in
the publications of many early workers, for instance Wallich( 1877) and Lohmann ( 1902 ). So, schematic cross-sectionsof coccoliths based on LM observations of coccospheres
require careful interpretation.

for April, 1950).
89

Journal of Namtoplankton Research, 20, 2, 1998.

JR. Young, R.W. Jordan. L. Cros.: Notes on nrumoplankton systematics... , p. 89 - 99.

2. In the particular case of[/. sibogae var. sibogae,
the distal shield is smaller than the proximal shield and isparticularly hard to obsetVe. Lecal's drawing (our Plate 1,
Figure 3) is by no means unreasonable as a cross-sectionof U. sibogae var. sibogae drawn from a coccosphere (cf.
Plate 3, Figures 7, 8). Two features of it are indeed morecharacteristic of U. sibogae var. sibogae than of N.
coccolithomorpha (auctt.): it has a flat proximal shield anda distinct distal flange. The continuation of the proximal
shield across the central area is incorrect for both
coccoliths.
3. Lecal's work contains many taxonomic idiosyncrasies, e.g. Helicosphaera carteri is variously
identified as: Coccolithus pe/agicus, Coccolithus
tesselatus and Cocco/ithus carteri. Consequently, hertaxonomic work requires critical assessment.
4. Lecal-Schlauder (1950) differentiated N. coccolithomorpha from U. sibogae on the grounds that U.
sibogae coccoliths have an open central-area (,possedant
un pore veritable"), unlike those of N. coccolithomorpha(,tremalithes afond plein"). In fact, both forms have open
central-areas, although it might be possible from LM
obsetVations to erroneously conclude that U. sibogae
coccoliths have a closed central-area.
5. Lecal never seems to have recorded U. sibogae
in her publications (we have checked almost all of them),
even though it is usually a common component of
nannoplankton assemblages. Therefore, it is quite likelythat she consistently identified V. sibogae as N.
coccoli thomorpha.
6. The drawing of a large cell (our Plate 1, Figure 1)
also resembles U. sibogae far more closely than it does N.
coccolithomorpha (auctt.)- in particular, large cells withvery numerous coccoliths are typical of U. sibogae var.
sibogae (compare Plate 1,Figure6).
7. Lecal-Schlauder (1950) described N. coccolithomorpha coccospheres as often containing several
cells (,Les spores se forment dans les cellules adultes: onpeut en distinguer quattre, l'interieur des plus grands
stades"). This is a characteristic feature of U. sibogae var.
sibogae.

holococcoli.th combinations (e.g. Coccolithus pelagicus- ,Crystalloiithus hyalinus'), the original name of thealternate phase can continue to be used in an informal,
non-Linnaean sense and, in this context, tile nomenclatural
niceties of the exact identity of the type specimen isirrelevant. This solution may be convenient to allow
unambiguous communication in, for instance, nannofloral
analyses. Also, it should be noted that two varieties of N.
coccolithomorpha are conventionally distinguished: N.
coccolithomorpha var. coccolithomorpha (large coccoliths and a wide central-area) and N. coccolithomorphavar. nishidae (small coccoliths with a narrow central-area).
Until it is established whether and how these correlatewith ceratolith varieties, the current varieties will need to
be used at least informally. (2) More correctly, the cells canbe identified as Ceratolithus cristatus (planolith phase),
which can be abbreviated to C. cristatus (P-phase), andthe coccoliths as C. cristatus planoliths. Tllis solution should
obviously be used in contexts where biological meaning isparamount, and hopefully will gain increasing currency.
NB Several workers have referred to different lifecycle phases as forma of a single species, e.g. C. pelagicus
f. pelagicus and C. pelagicus f. hyalin us. However, thisconvention is contrary to basic principles of the ICBN andso is not acceptable (Paul Silva, pers comm., 1998; John
Green, pers comm., 1998; Jordan et al., 1995; Cros et al., inpress).
Ceratolithus cristatus diversity
Not only are ceratoliths and two types ofheterococcoliths
formed by C. cristatus, but also each of these is known in
two main varieties, and a range of combination coccospheres have now been recorded. A brief summary istherefore in order, although exhaustive details do not need
to be given since the literature on the species is alreadysubstantial.
Summary of Iith types produced by Ceratolithus:
1. Ceratoliths Horseshoe-shaped nannoliths. Three types
have been described: Ceratolithus cri status var. cristatus- the typical form (Plate 3, Figures 5, 6); Ceratolithus
cristatus var. telesmus- a form with longer arms that cuiVetogether to almost touch; Ceratolithus cristatus forma
rostratus -an ornate form with an apical beak (Plate 3,
Figures I, 2, 4). (NB This form has not been validly described
and, as discussed below, it seems likely that it is simply amore heavily calcified morphotype of C. cristatus var.
cristatus, so it is referred to here informally as a rostratustype ceratolith).
2. Hoop-coccoliths Simple hoop-shaped heterococcoliths. In TEM, these can be seen to be formed ofalternating, large, rectangular crystal-units and muchsmaller, interlocking, rectangular crystal-units- (Norris,
1971; Manton eta/., 1977; our text-figure IB). In tile SEM,
only the larger crystal-units are visible. Norris (1965)
describes them as forming rims to a subtending organic
baseplate. Our obsetVations suggest that two forms occur,
although it is possible they intergrade: robust hoops typically 4-5Jlm across with rims 0.2-0.4Jlm wide. Thesea

Nomenclatural conclusions
From this, we conclude that the species described by LecalSchlauder (1950) was indeed U. sibogae var. sibogae, eventhough subsequent workers have assumed from thedrawing (Plate 1, Figure 3) that it was the quite different
form, conventionally identified as N. coccolithomorpha.
So, the name Neosphaera coccolithomorpha is a juniorsynonym of Umbilicosphaera sibogae .
Following this, the correct name for the alga which
produces ceratoliths, hoop-shaped coccoliths and,Neosphaera' planoliths is Ceratolithus crista/us. Thisconclusion avoids the nomenclatural nightmare which waspossible when Neosphaera seemed likely to be a seniorsynonym of Ceratolithus, but leaves the relatively trivial
problem of how to refer to the coccoliths and coccospheres
of ,N. coccolithomorpha'.
Two basic solutions are possible and, almost
inevitably, both will be used. ( 1) As in heterococcolith-

typically remain intact in SEM preparations (Plate 2, Figure
90JR. Young, R.W Jordan, L. Cros.: Notes on na1moplankton systematics..., p. 89- 99.

2); delicate hoops- typically 4-6J.lln across with rims about
0.1-0.211111 wide. These tend to disintegrate in SEM
preparations (Plate 2, Figures 1, 2; Plate 3, Figures 1-7).
3. Planoliths Heterococcoliths with a single shield,
formerly assigned to N coccolithomorpha. They varyconsiderably in size and central-opening diameter but two
main varieties are usually distinguished (Kleijne, 1993;
Jordan & Kleijne, 1994 ; Jordan & Green , 1994) .
Measurements given below are from Kleijne (1993): var.

outer-tube element "-....
shield element
inner-tube
element

likely growth origin(i.e. locus of proto-coccolith ring)t

A. STRUCTURE OF PLANOLITH COCCOLITHS

main crystal-units

I "....______,..__]'='l /---~
peg-like connecting crystal-units

B. STRUCTURE OF HOOP CO.CCOLITHS(redrawn from Manton et al., 1977)

Journal of Naru10plankton Research, 20, 2, 1998.

cocco/ithomorpha with a large central-opening (opening
diameter 0. 4-0.5 x coccolith diameter), and usually large (6lOJ.lln), although small forms (4-5jll11) also occur (Plate 2,
Figures 3-6); var. nishidae- with a narrow central-opening(opening diameter 0.15-0.3x coccolith diameter), and small
coccolith diameter (4-7jll11) (Plate 3, Figure 4).
Summary of combination coccosphcres observed
A. Robust hoops surrounding ceratoliths (type indeterminable). Figured by Knappertsbusch in Winter & Siesser(1994) andAlcober & Jordan (1997).
B. Delicate hoops surrounding large, strongly
ornamented ceratoliths, especially rostratu s-type
ceratoliths. Figured here (Plate 2, Figure 1; Plate 3, Figuresl-3, 4-6) and by Norris (1965 , fig.4), Cros et al. (in press)
and, perhaps, by Borsetti & Cati ( 1976, p1.17, figs 9, 13).
This appears to be a very characteristic association: wehave found several examples.
C. Delicate hoops with nishidae planoliths; either
type of coccolith may form the inner layer. Figured by
Alcober & Jordan ( 1997), Cros et al. (in press) and Borsetti& Cati (1972, pl.43, fig.2). Again, this appears to be acharacteristic association, and we have found several
examples.
D . Delicate hoops with coccolithomorphaplanoliths. Figured here (Plate 2, Figure 3). This seems aless common association.
E. Robust hoops with co ccolithomorphaplanoliths. Figured here (Plate 2, Figure 2) and by Alcober& Jordan ( 1997).
In addition, nishidae planoliths occur on or next totwo of the five rostratus ceratoliths figured by Borsetti &Cati (1976, pl.17, figs 9, 10, 16), and we have found one
similar possible association (Plate 3, Figure 4).
It has been speculated that heterococcolithholococcolith associations represent a haplo-diplontic lifecycle, with heterococcoliths on the diploid phase andholococcoliths on the haploid phase (Billard, 1994; Young& Bown, 1997), although this is still unproven (Cros et al. ,in press). The range of combinations encountered makes
it difficult to fit Ceratolithus into this model. The simplest
hypothesis, however, would seem to be that the ceratoliths
are equivalent to holococcoliths and produced on haploidcells, whilst the planoliths are normal heterococcoliths
produced on diploid cells, with the hoop-coccoliths being
special heterococcoliths produced during, or prior to, phasechanges. The frequent association of the rather rare
rostratus-type ceratoliths with hoop-coccoliths suggeststhat this may be a morphotype developed in association
with the phase change, rather than a genotypic variant.
Obviously, further observations on this unusual species
are needed.
Notes on C. cristatus planoliths(,Neosphaera' coccoliths) ·Identification:
C. cristatus planoliths are easily identified in the SEM androutinely recorded in the plankton. They are, however,
harder to identify in the LM and, consequently, are lesswidely recorded in the fossil record. In particular, they aresuperficially similar to Umbilicosphaera sibogae and U.

Text-figure 1: Light micrographs of Ceratolithus planoliths.

91

Journal of Nannoplankton Research, 20, 2, 1998.

JR. }oung. R.W Jordan, L. Cros.: Notes on nrumoplankton systematics.. , p. 89- 99.

Structure:

Phase contrast

Mid-focus

High-focus

Text-figure 2: Structure of Ceratolithus coccoliths. A Reconstruction of the structureof C. cristatus planoliths. Three crystal-units drawn in oblique-view, showinginterconnections of the shield, inner-tube, and outer-tube elements. B. Structure ofhoop-coccoliths, redrawn from Manton et al. ( 1977). These details are only visible
in TEM.

rotula placoliths. They can be distinguished, however, by

In the SEM, the shield of the C. cri status
planoliths is clearly formed of a single cycle
ofradial elements, whilst the tube is formedof discrete inner and outer cycles (Plate 2,
Figures 4-6; Kleijne, 1993). The outer-cycle
elements are easily observed to beconnected to the shield elements, and show
clockwise imbrication (Plate 2, Figure 5). The
inner-tube elements are oriented vertically(Plate 2, Figure 6). The inner- and outer-tube
elements are probably formed from the same
crystal-unit as the shield and outer-tube
since: (I) connections between inner- andouter-tube elements are sometimes visible
in distal view; (2) in proximal view, there isno evidence of discontinuity between the

inner-tube and shield elements. This structure is summarised in tex.t-figure lA.
LM observations support this : when seen in sideview with a gypsum plate (cf. Young, 1992), the entire
coccolith appears to be formed of a single cycle of crystalunits with steep c-axes. Our LM observations suggest thatthe c-axes are oriented with an inclination of about 60°
from the horizontal and an azimuth (i.e. orientation in planview) of about 45° from radial. The steep inclination means
they can be tentatively identified as V-units, sensu Younget al. (1992). By contrast, the placoliths ofUmbilicosphaera (including U. rotula) and otherCalcidiscaceae have a proximal shield ofR-units and a distal
shield of V-units. So, Young & Bown (1997) placed N.
coccolithomorpha in heterococcoliths incertae sedis.
The very distinctive structure of ,N. coccolithomorpha' planoliths makes it unlikely that they were
derived from any known placolith by loss of the distal
shield. Instead, we may speculate that they may have been
derived from the hoop-shaped coccoliths of Ceratolithus
by development of a proximal shield.
Descriptions of the structure of the hoop-shaped
coccoliths of Ceratolithus have been given by Norris (1971)
and Manton et al. ( 1977), based on TEM observations.
They apparently worked independently, but theirdescriptions of the structure are identical. The hoops areformed of alternating, large, rectangular crystallites andinterlocking, much smaller, rectangular crystallites (textfigure lB). If the planoliths were derived from this structure,then we might exvect only the larger crystal lites to develop,
giving rise to planoliths almost entirely formed from a single
crystal-unit. So, the structure of the hoop and planolithcoccolith-types are compatible with the hypothesis thatthe planoliths are a modified form of the hoop-shaped
coccoliths.

their appearance in cross-polarised light (text-figure 2).
When the coccolith is in focus, the shield is dark and thetube bright, without an obvious extinction cross. At a focal
plane just above the specimen, a strong extinction cross isseen, with the arms offset by nearly 45° from radial andshowing distinct curvature. By contrast in
Umbilicosphaera, although the tube is brighter than theproximal shield, it is usually clear that the proximal shield isbirefringent, and the extinction cross shows straighter andmore nearly radial anns.

Synonym- Cyclolithella annula (Cohen, 1964) Mclntyre& Be, 1967:
Cohen (1964) described as a new species, ,Coccolithites
annulus', the C. cri status planoliths. This name has been
widely used by palaeontologists, although decreasingly
so of late. Cohen 's description is based on isolated
coccoliths viewed in the LM only, but it is carefully done
and the identity of the illustrated specimens isunambiguous. This epithet has been considered a juniorsynonym of N. coccolithomorpha; by our interpretation,
it is a junior synonym of C. cristatus. NB Cyclolithus
anulus Lecal (1967) is a quite different coccolithophore,probably related to Umbilicosphaera, see Kleijne (1993)
and Young (1998).

Fossil record:
The fossil record of C. cristatus (P-phase) coccoliths isdifficult to assess, since few workers have consistently
identified it. Our observations suggest that it is frequently
present in Quaternary deposits and occurs sporadically in
the Pliocene. The earliest unambiguous records are
specimens from theEarlyPiiocene, zone NN12, illustrated
by: Perch-Nielsen (1977, pl.41, fig.7) as Umbilicosphaera
sp. from DSDPSite 354 (S Atlantic), and by Su (1996, p1.5,
fig.9) as N. coccolithomorpha from ODP Hole 659A,(subtropical N Atlantic). These records broadly correlatewith the first occurrence of Ceratolithus ceratoliths, so it
will be interesting to see if the fossil record of the two

Taxa cited

Cerato/ithus cristatus Kamptner, 1950
Synonyms: Cyclolithella annul a (Cohen, 1964)
Mclntyre & Be, 1967
Neosphaera coccolithomorpha var. nishidae Kleijne,
1993

nannofossils shows parallels.

92

J.R. Young, R.W. Jordan, L. Cros.: Notes on nannoplankton systematics..., p. 89- 99. ·Ceratolithus cri status var. telesmus (Norris, 1965) Jordan&Young, 1990
Ceratolithus cristatus f. rostratus Borsetti & Cati, 1976
[Invalid, no diagnosis. We do not validate this form here
since we believe the morphotype is likely to be related to
the life-cycle and so should not be given any formal
taxonomic status]
Cyclolithus anulus (Lecal, 1967)
Coccolithus pelagicus (Wallich, 1877) Schiller, 1930
Helicosphaera carteri (Wallich, 1877) Kamptner, 1954
Umbi/icosphaera sibogae var. sibogae (Weber-van Bosse,1901)Gaarder, 1970
Synonym: Neosphaera coccolithomorpha LecalSch1auder 1950
Umbilicosphaera rotula (Kamptner, 1956) Varol, 1982
Synonym: Geminilithella rotula (Kamptner, 1956)
Backman, 1980

Acknowledgements
We are very grateful to Isao lnouye (Tsukuba) for allowing
use of the micrograph reproduced as Plate 1, Figure 5, andto Alexandra Broerse (VU Amsterdam) for loaning othercomparative material. Amos Winter (Mayaguez University)
collaborated with RWJ on sampling and study of Puerto
Rican material. Jose Fortuno assisted LC with electron
microscopy of the Mediterranean samples. Collaboration
between JRY and LC was supported by the EC TMR
CODENET project, and tllis is a publication of the project.
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Thomsen , I-I.A., 0stergaard, J.B. & Hansen , L.E. 1991.
Heteromorphic life histories in arctic coccolithophorids(Prymnesiophyceae). Journal of Phycology, 27: 634-642.
Varol, 0 . 1982. Calcareous nannofossils from the Antalya Basin,
Turkey. Neues Jahrbuch jilr Geologie und Paliiontologie.
Monatshejte, 4: 244-256
Wallich, G.C. 1877. Observations on the coccosphere . Annals
and Magazin e ofNatural Hiswry, 19: 342-350.
Weber-van Bosse, A. 1901. Etudes sur les Algues de I' Archipel
Malaisien. ill. Note preliminaire sur les .resultats algologiquesde !' expedition du Siboga. Annates de Jardin Botanique
Buitenzorg, 17(SC1'.2): 126-14 I.
Winter, A. & Siesser, W.G. 1994. Atlas ofliving coccolithophores.
In: A. Winter & W.G. Siesser (Eds). Coccolithophores: 107160. Cambridge University Press, Cambridge.

93Journal ofNannoplankton Research, 20, 2, 1998.

J.R. Young, R.W Jordan, L. Cros.: Notes on nrumoplankton systematics..., p. 89- 99.

Young, J.R. 1992 . The description and analysis of coccolith
structure . In: B . Hamrsmid & J .R. Young (Eds).
Nannoplankton Research , I . General topics, Mesozoic
biostratigraphy. Knihovnicka ZPN, 14a: 35-71.
Young, J.R. 1998. Neogene. In: P.R. Bown (Ed.). Calcareous
Nann ofossil Biostratigraphy: 224-265 . British Micropalaeontological Society Publications Series, Chapman & Hall.
Young, J.R. In press. Calculation of Coccolith Volume and it use
in Calibration of Carbonate Flux E stimates. Deep-Sea
Research If.

Young, J.R. , Bergen, J.A., Bown, P.R. , Burnett, J.A. , Fiorentino.
A., Jordan, R.W., Kleijne, A., van Niel, B. E., Romein, A.J.T.
& von Salis, K. 1997. Guidelines for coccolith and calcareous
nannofossil terminology. Palaeontology, 40: 875-9 12.
Young, J.R. & Bown, P.R. 1997. Cenozoic calcareous nannoplankton classification. Journal of Nannoplankton Research ,19(1): 36-47.
Young, J.R., Didymus, J.M ., Bown, P.R., Prins, B. & Mann, S.
1992. Crystal assembly and phylogenetic evolution inheterococcoliths. Nature, 356 : 516-518.

Plate 1
Umbilicosphaera sibogae var. sibogae

Figs 1-4: Reproductions of the illustrations from Lecal-Schlauder (1950) illustrating the description of ,Neosphaera
coccolithomorpha' .
Fig.1: Drawing of ,adult' cell (fig.4 ofLecal-Schlauder, 1950)
Fig.2: Plan-view of a coccolith (fig.5 ofLecal-Schlauder, 1950)
Fig.3: Cross-section (,coupe optique") of a coccolith (fig.5 ofLecal-Schlauder, 1950)
Fig.4: Light micrograph of a cell (, stade bulle en lumiere parallcle") (pi. VI, fig.4 ofLecal-Schlauder, 1950).
Figs 5-8: Comparative illustrations of unambiguously identified U. sibogae var. sibogae.
Fig.5: Light micrograph of a coccosphere of U. sibogae var. sibogae courtesy of Prof. Inouye, Tsukuba University.
Fig.6: SEM ofa large, partially collapsed coccosphere specimen. From N Atlantic, Sample 11290/2/5 (200m water-depth).
Scale-bar= 1f.Ull.

Fig. 7: Reconstruction of coccolitl1 profile of U. sibogae var. sibogae from Young (in press)- note similarity with Figure 3.
Fig.8: Detail from same coccosphere as Figure 6. Scale-bar= 1 f.Ull.

94

J.R. )'Wig. R 11: Jordan. 1- C

1

FIJ . S. - N~o phaua coc olitho·morpha n p PI ue vu de face. Gro •1 ement · 6.000.

3

F11. 6. - N~o pha~r occolitho·morpha n. p
upe pllque dune plaque. Gro 1 ement: 6.000.

9

Journal of Narmoplankton Research, 20, 2, 1998.

J.R. }oung. R.W Jordan. L. Cros.: Notes on nannoplankton sy~tematics ... , p. 89- 99.

Plate2
Ceratolithus crb.tatus
Scale-bars= l)lm in Figures l, 4-6; = lO)lm in Figures 2, 3

Figs 1-3: Examples of combination coccospheres.
Fig.l: rostra/us-type ceratolith surrounded by collapsed coccosphere of delicate hoop- coccoliths. Note that the hoopcoccoliths occur both on top of and underneath the ceratolith, supporting the inference that the ceratolith was inside thecoccosphere. From NW Mediterranean (40°N, 1°E), Fans-! Stn.l23( 137), 25m.
Fig.2: Combination coccosphere of coccolithomorpha planoliths surrounding robust hoop-coccoliths. From Puerto
Rico.
Fig.3: Combination coccosphere of delicate hoop-coccoliths surrounding coccolithomorpha planoliths. From Puerto
Rico.
Figs 4-6: SEMs of C. cri status planoliths showing the ultrastructure. All from N Atlantic, Sample 11290/2/12 (26°N,
30°W, lOm water-depth).
Fig.4: Proximal view. Note distinct kink in elements near inner margin. This may represent the locus of the protococcolith ring.
Fig.5: Detail of outer-tube cycle, showing clockwise imbrication and extensions running anticlockwise on the distal
surface toward the inner-tube cycle elements. Inset: view of entire planolith.
Fig.6: Detail of inner-tube cycle, showing subvertical orientation. Same specimen as Fig.5.

96

•p

PLAT

97

Journal of Nam10plankton Research, 20 , 2 , 1998.

J.R.. You ng, R.W Jordan. L. Cros.: Notes on nrumoplank1on sy;1ematics... , p. 89 - 99.

Platc3
Ceratolithus cristatus
Scale-bars= 111m in Figures 1, 3, 4, 7; = !011min Figures 2, 5, 6

Fig. I: rostratus-type ceratolith with remains of a few broken delicate hoop-coccoliths lying on it. From N Atlantic,
Sample ST1131l (26°N, 45°W), 40m.
Figs 2-3: rostra/us-type ceratolith surrounded by collapsed coccosphere of delicate hoop-coccoliths. From NW
Mediterranean, Fronts-96, Stn. 013 (31 °N, 4°E), lOm.
Fig.4: Association of a rostratus-type ceratolith, a simple ceratolith, three nishidae~type planoliths, and remains ofdelicate hoop-coccoliths (inside the planoliths). This association is suggestive but could be in part accidental. FromNW Mediterranean, Fans-! , Stn. 123(137) (40°N, 1°E), 40m.
Figs 5-6: Association of two highly ornamented ceratoliths inside a collapsed coccosphere of delicate hoop-coccoliths.
From N Atlantic, Sample ST 11314/3 (26°N, 42°W).
Fig. 7: Detail of delicate hoop-coccoliths. From NW Mediterranean, Fans-! , Stn. 100(113) (40°N, I 0 E), 5m.

98

PL

3

99